1. Field
The present disclosure relates to a genetically engineered yeast cell having acid tolerance, a method of preparing the same, and use thereof.
2. Description of the Related Art
Organic acids are widely used in a variety of industries. For example, lactate is an organic acid widely used in a variety of industrial fields, including food, pharmaceutical, chemical, and electronic industries. Lactate is a colorless, odorless, water-soluble, low-volatility material. Lactate is also not toxic to the human body, and is used as a flavoring agent, a sour taste agent, a preserving agent, or the like. Additionally, lactate is used as a source of polylactic acid (PLA) that is an environmentally friendly, biodegradable plastic known as an alternate polymeric material.
Organic acids are dissociated into hydrogen ions and their own negative ions at a higher pH than their own pKa value, for example, under neutral conditions. However, an organic acid, for example, lactic acid, is present in the form of a free acid without an electromagnetic force under acidic conditions lower than its own pKa value. The negative ion may not permeate a cell membrane, but the free acid form may permeate a cell membrane. Therefore, the free acid form may flow into the cells from extracellular environments where the concentration of the organic acid is high, thus lowering an intercellular pH level. Further, there is a disadvantage that an organic acid present as negative ions is isolated in the form of salt by an isolation process involving the addition of a salt. As a result, cells lacking acid-tolerance may become inactive and nonviable under acidic environments containing lactic acid
Accordingly, there is a need for microorganisms with acid-tolerance.